The pair wowed crowds as they stormed through an epic 50-song set list

Pop beauty Rihanna and rapper Eminem hit the stage on Thursday night for the opening date on their Monster tour.

The six-date tour kicked off at the Rose Bowl in Pasadena, California, and according to fans, they pulled off a show-stopping performance as they rattled through an epic 50-song set list.

26-year-old Rih slipped in and out of a variety of racy (and some very bizarre) outfits, like these flame print pants, while 41-year-old Eminem rocked camo pants, plain tees, and hoodies.

Speaking about working with Em in the past, Rihanna said: "The moment I worked with him on Love the Way You Lie, I wanted to work with him again, and we did Love the Way You Lie Part 2.

(Photo: FameFlynet)

"And then I wanted to work with him again. I just love working with Eminem. He's just one of my favourite rappers, and his lyrics- he's a true poet, and I enjoy that about him."

Other stars who turned up to the concert, included supermodel Adriana Lima and actress Ellen Pompeo.

The pair will play Pasadena for one more night before making their way to New Jersey and will finish up in Detroit.

The pair kicked off their tour just after fancy pants Rihanna trademarked her last name for apparel, underwear and beauty products.

The 'S&M' singer - real name Robyn Rihanna Fenty - has put a trademark on her surname Fenty sparking speculation that she is planning to launch her own clothing line.

(Photo: FameFlynet)

According to swaggernewyork.com , the R&B star has laid claim to her last name by filing trademark documents which prevents another person using the name for clothing, lingerie, cosmetics and swimwear.